1、南昌航空大学科技学院（论文）-附录AFifthMotionandVibrationConference/MOVIC2000/Sydney/Australia/4/-8/December2000byUniversityofTechnology/SydneySPEED-ADAPTEDTRAJECTORIESINTHECASEOFINSUFFICIENTYDRAULICRESSUREFORTHEFOUR-LEGGEDLARGE-SCALEWALKINGVEHICLEALDURODanielGermann/JorgMullerandManfredHillerGerhard-Mercator-Unive
2、rsitatGHDuisburgFachgebietMechatronik/Lotharstrae1/47057Duisburg/GermanyEmail/fgermann/mueller/hillergmechatronik/uni-duisburg/deABSTRACTWhenoperatingwalkingmachines/onlyacoordinatedmovementofallcylindersand/ormotorscanleadtosafe/stablewalking/ThelargehydraulicallydrivenwalkingmachineALDURO/whichisi
3、nvestigatedinthispaper/hasnoexternalpowersupply/andthereforethesizeoftheon-boardhydraulicpowerpackanditsdieselengineislimitedbyitsweight/Whenmovingseveralcylinderswithhighspeed/thehydraulicsupplycanbecomeinsufficientandtheresultingtrajectoriesoffeetandplatformcanbecomeunpredictable/WhentheALDUROisne
4、aritsstabilitylimitsuchbehaviourcanleadtoinstabilityandtopplingofthesystem/Theproposedsolutionunderdiscussionhereistoobservethepositionerrorsandtimederivativesforthecylindersandbasedonthisreducethespeedwhennecessary/1/INTRODUCTIONThesysteminvestigatedinthispaperistheAnthropomorphicallyLeggedandWheel
5、edDuisburgRobot(ALDURO)/Itconsistsofaplatformof2/0mby2/2mwithacabinfortheoperatorandfourlegs/each1/8mlong/Theestimatedweightis1200kg/Itcanbeusedasaquadrupedwalkingmachine(Fig/2)/andbyreplacingthetwohindfeetwithwheels/itcanalsobeusedasacombinedleggedandwheeledvehicle(Fig/1)/Thelattercombinestheadvant
6、agesofawalkingmachine-highmobility-withthestabilityandspeedofwheeledvehicles2/Whenoperatinginsteepanddangerousterrain/safetyplaysanimportantrole/Itmustbeguaranteedthatthecylindersfollowthecalculatedtrajectoriesexactlysinceawrongmovementmightcausetherobotto南昌航空大学科技学院（论文）-becomeinstable/ALDUROslegsare
7、hydraulicallydriven/withanopenhydraulicsystem/Normally/whenplanninghydraulicsystems/lowweighthasnohighpriority1/ForthewalkingmachineALDUROtheratiopowerperweightwasoptimized/Fig/1/CombinedLeggedFig/2/WalkingMachineandWheeledVehicleWhileactuatingseveralcylinderssimultaneouslyormovingveryfast/thevolume
8、flowofthehydraulicsupplybecomesinsufficientandtheresultingmovementsuncontrollable/Theproposedsolutionunderdiscussionhereisadecreaseinspeedofallcalculatedtrajectories/Thisisadmissibleaslongastherobotisstaticallystableatanymoment/Byobservingthepositionerrorsofthecylindersandtheirtimederivatives/adecis
9、ionistakenonwhethertodecreaseorincreasethespeedalongthetrajectories/Toensurethatallmovementsareinfluencedsimultaneously/themodel-time/uponwhichallcalculationsdepend/issloweddown/Thuswecanguaranteethatlegsandplatformcananddofollowtheprescribedtrajectories/Thisstrategyisbeingtestedonavirtualmodelofthe
10、ALDUROandisbeingtestedonavirtualmodeloftheALDUROandateststandinthelaboratory/consistingofasingleleginscale1/1/givingverygoodresults/Fig/3/Experimentalsetup2/EXPERIMENTALSETUP南昌航空大学科技学院（论文）-ThelegoftheALDUROisanthropomorphic/i/e/itisbasedonthegeometryandfunctionofthehumanleg/Thehipjointisasphericalba
11、lljointwiththreedegreesoffreedom(d/o/f/)andthekneearevolutejointwithoned/o/f/Thesejointsareactuatedwithhydrauliccylinders(Fig/4)/whereasthetwoadditionald/o/f/ofthefootarepassive/Tomakesolutionoftheexplicitinversekinematicspossiblewelockoneofthehipcylinders/Theexplicitsolutionofthedirectandinversekin
12、ematicsisshownindetailin4/Toexaminethedynamicbehaviouroftheleg/andtotestdifferentcontrolschemes/anexperimentalsetupforafullysizedlegwasdevelopedandbuilt(seeFig/3)/ItincludesallthehydrauliccomponentsthatwillbeusedonthefirstprototypeALDUROandisdrivenbyastationaryhydraulicpowerpackinthelaboratory/Theex
13、perimentalset-upisequippedwithanopenhydraulicsystemwitha15kWelectricalmotorandanaxialpistonpumpproducingavolumeflowof40l/minat200bar/Thisissmallerthanwhatwillbeusedontherealsystem/whichwillbepowerdbya27kWdieselengine/Fortestswithaninsufficienthydraulicflow/asecondsetoffourhydrauliccylinders(asusedto
14、moveoneleg)ismountedonthefloornexttotheteststand/Anopticalfieldbusforthetransferofthesensorandactuatordatabetweentheteststandandthecontrolcomputer(withreal-timeoperatingsystem)isalsoinstalled/Thehydrauliccylindersincludepositionandpressuresensorsthatareusedascontrollerinputs/Thusdynamictestscanbecar
15、riedouttoexaminetheco-operationbetweenthemechanicalandhydrauliccomponentsandtheelectroniccontrolsystem/Thehipplateoftheexperimentalset-upismountedonapairoflinearbearings/andthusismobileinverticaldirection/Whencombinedwiththefoot/asshowninFig/3/orthepassivewheelusedonthehindlegofthecombinedleggedandw
16、heeledsystem/thisallowsloadingtestsonthelegwhileperformingwalkingmotions/Mechanicalstopsbelowthehipplateallowthefoottobeliftedintheswingphaseofthewalkingmotion/Thefirst(unloaded)testshaveshownthemobilityoftheanthropomorphiclegmechanismtobeverygood/andtheopticalfieldbussystemhasalsoproventobereliable
17、/南昌航空大学科技学院（论文）-3/SPEEDADAPTATION3/1InsufficientHydraulicFlowAsalreadymentioned/theweightandsizeoftheonboardpowerpackislimitedandhastobekeptlow/Whenmovingseveralcylinderssimultaneouslyorwithahighspeedthehydraulicsupplycanbecomeinsufficientandthepressurewillcollapse/Inthiscasetheresultingmovementdepe
18、ndsmainlyonthesizesoftheproportionalvalvesandexternalloadsonthecylinders/Thetrajectoriesofthefeetandplatformbecomeerratic/WhenALDUROisnearlimitofitsstabilitysuchbehaviorscanleadtoinstabilityandtopplingofthesystem/Asthesafetyissueisaveryimportantone(peoplecouldbeharmed)thispressurecollapsehastobeprev
19、ented/Toinvestigatethisbehavior/acircularmovement(radius0/2m/velocity0/5m/s)ofthefootinthehorizontalplane1mbelowthehipwaschosenasareference/Thistrajectoryhastheadvantagethatitactuatesallthreeunlockedcylinders/Withatypicalverticalsteppingmovementofthefootthesidewayscylinder(no/2inFig/4)isnearlystationary/Theinversekinematicsforthemappingofthefootco-ordinateintotheco-ordinatespaceforthethreecylindershasbeendevelopedintheC+programmingenvironmentMaaaaBILE3/
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